Normally Yellowstone earthquake swarms contain 10 to 50 earthquakes. Even up to 100 isn’t unusual. But, the quake swarm that hit Yellowstone a couple weeks back, which included a magnitude 4.5 event, hasn’t stopped yet. In fact, it’s risen to nearly 800 or more. That’s 8 to 10 times the usual amount—so what gives? Hopefully not the Earth’s crust, or we’ll all be blown to kingdom come.
Luckily, that’s most likely not the case, given that the chance of Yellowstone erupting today is about 1 in 730,000. While the earthquake swarm may have been caused by magma moving beneath the Earth’s crust, it’s more likely to be the result of some movement along a minor fault line in the area.
The largest earthquake swarm in the region occurred in 1985, when a swarm of more than 3,000 quakes struck in 3 months in the exact same area. And we’re all still alive.
Predicting when the next volcanic eruption will occur is currently impossible. But Yellowstone certainly has a destructive history. According to the USGS, “Over the past 2.1 million years Yellowstone volcano has had three immense explosive volcanic eruptions that blanketed parts of the North American continent with ash and debris. Each of these eruptions created sizable calderas: basins formed by the collapse of the ground after the evacuation of subsurface magma reservoirs. The Yellowstone Caldera, which comprises nearly one-third of the land area in the park, formed 0.64 million years ago and was followed by dozens of less explosive but large lava flows, the last of which erupted 70,000 years ago.”
While the worst-case scenario of a Yellowstone eruption would result in a volcano-induced Ice Age, with much of North American blanketed in ash up to three feet deep, scientists say this isn’t likely to occur. “Yellowstone hasn’t erupted for 70,000 years, so it’s going to take some impressive earthquakes and ground uplift to get things started,” according to the USGS scientists.
But they agree that an eventual eruption is a certainty—and one that would come with warning signs: “Besides intense earthquake swarms (with many earthquakes above M4 or M5), we expect rapid and notable uplift around the caldera (possibly tens of inches per year). Finally, rising magma will cause explosions from the boiling-temperature geothermal reservoirs. Even with explosions, earthquakes and notable ground uplift, the most likely volcanic eruptions would be the type that would have the minimal effect outside the park itself.”
North America’s future seems safe from volcanic annihilation—for now—but what about the rest of the world? A catastrophic supervolcano explosion would send so much ash into the atmosphere it would block the sun for up to eight years, creating a volcanic “winter” that could lead to the mass extinction of humans, animals, and plants on our planet.